Field of the Invention
The invention relates to a device for thermally insulating casing parts of a steam turbine, in particular between an inner casing and an outer casing of a steam turbine having a spiral inflow.
Published, Non-Prosecuted German Patent Application DE 36 17 537 A1, for example, discloses an inflow casing of a steam turbine having a spiral inflow. In this case, between two casing parts of the steam turbine, which are supported against one another or rest on one another, in particular in the region of a torque support or a supporting bearing of an inner casing in the outer casing, large forces of, for example, about 1000 to 2000 kN and large temperature differences between the outer casing and the inner casing normally occur. Thus a high torque is produced on the respective support or bearing lug on account of the high pressure of, for example, 60 bar of the steam flowing into the steam turbine. The force which is thus produced on the respective support may be about 150 tons at this steam pressure.
Specified in Published, Prosecuted German Patent Application No. 1 055 549 is a shim which is disposed in a region of a dividing flange of a turbine outer casing between the turbine outer casing and a supporting lug of the turbine inner casing, the supporting lug resting on the turbine outer casing. In this case, the shim is a pressure plate that has holes that limit supporting cross sections. The intended purpose of the pressure plate is to expressly prevent inadmissible stresses from occurring in the flange of the outer casing if play present in the cold state between the supporting lug of the inner casing and the flange of the outer casing is bridged as a result of pronounced thermal expansions.
This is achieved by holes in the pressure plate which ensure plastic deformation of the pressure plate and thus a reduction in the input of stress into the flange of the outer casing.
A steam turbine having a spiral inflow is specified in each case in Swiss Patents CH 665 450 A5 and CH 666 937 A5. In the region of the respective flanges of the outer casing, unspecified components are disposed between the outer casing and the inner casing.